It is commonly known that upon retorting in sauces starchy foods such as pasta, rice, or vegetables lose their structural integrity. The foods become mushy, agglomerate and lose their structural appeal.
Firm or non-mushy macaroni, vegetable and rice textures are highly desirable for consumer acceptance in retorted or shelf stable food products. However, due to the severe high temperature, pressure and length of heating, fine textural attributes of macaroni, rice and vegetables are difficult to achieve.
Various attempts have been made to overcome the textural problem in retortable foods. Most efforts have been directed toward reformulating the composition of the starchy food component of the retortable foods without reformulating the sauces in which the starchy food is admixed. While this approach has worked reasonably well, it has not entirely solved the problem.
Less successful efforts have been attempted in engineering sauces used in retortable foods in order to increase the firmness of the starchy food or vegetable retorted therein. U.S. Pat. No. 4,597,976 discusses reformulating the sauce in order to improve the textural properties of the retorted food product. The '976 patent specifies acidifying the sauce to a pH of less than 4.6 to reduce retort time and thus limit textural degradation of the starchy component of the food product.
U.S. Pat. No. 4,291,066 to Anema discloses the method of producing a concentrated soup, sauce, gravy, or dessert which can be reconstituted into a lump-free product. Anema stresses the importance of retaining the starch of the concentrate in an ungelatinized state. To ensure the starch is not gelatinized, Anema pasteurizes instead of retorting. Pasteurizing is a much gentler treatment than retorting. Pasteurizing involves heating a sample only up to about 212.degree. F. (typically 140.degree.-185.degree. F.). Although certain pathogens and spoilage organisms are eliminated, this process does not sterilize the product as does retorting.
In order to retard microbial growth, the composition of Anema has a low water activity (A.sub.w). The A.sub.w of the Anema composition is depressed by adding an "osmotic pressure increasing agent" such as starch hydrolysates including maltodextrins or glucose syrup solids having a DE between 10-42, hydrolyzed amylopectin, and/or sucrose. "Water-activity depressing agents" including salts and humectants are added in combination with the osmotic pressure increasing agents in order to maintain Anema's A.sub.w below 0.92.
The present invention has a A.sub.w above 0.92 and is retorted. The sauce of the invention does not require diluting before consumption as required by Anema. The invention sauce optionally contains starch which is added as a thickening agent. However, unlike Anema, the starch of the present invention is gelatinized during the abusive treatment of retorting.
The present invention, a method of preserving the physical integrity of starchy foods and vegetables which are thermally treated under pressure (retorted therein) is a great improvement over the existing art. The method involves admixing starchy foods or vegetables with a sauce and then retorting or aseptically treating said mixture. A sauce which does not require reformulated starch components nor an acidified pH to enhance firmness in retortable pasta, rice, and vegetables is new and unique. The invention sauce is most effective in preserving the structural integrity of foods which absorb significant amounts of water during retort. Accordingly, the invention works best when admixed with dehydrated or dried foods.